1. Field of the Invention
The present invention relates generally to a tape cleaner for a magnetic recording and reproducing apparatus and, more specifically, to a tape cleaner that mechanically scrapes against the magnetic tape of a tape recorder.
2. Description of the Background
In a conventional magnetic recording and reproducing apparatus such as a tape recorder and so on, a tape cleaner is used for removing dust, magnetic powder and the like from a magnetic tape.
FIG. 7 shows a construction of a tape cleaner of a magnetic recording and reproducing apparatus, and FIG. 8 shows an enlarged view of a portion of the tape cleaner of the magnetic recording and reproducing apparatus shown in FIG. 7. The conventional tape cleaner of the magnetic recording and reproducing apparatus will be described below with reference to FIGS. 7 and 8.
In FIG. 7, reference numeral 2 designates a supply reel, 3 a takeup reel, 4, 5, 7, 9, 10, 12, 13, 14, 17, 18, 19 and 21 fixed or rotary tape guides, respectively. Shown at 6 is a guide pin, 11 a rotary magnetic head apparatus on which a magnetic head (not shown) is mounted, 8 a full erase head, 15 a control head (CTL) for recording/reproduction, 16 a recording/reproducing head, and 20 a control head (CTL) for recording confirmation.
In the figure, reference numeral 24 designates a blade, the material of which is sapphire or ruby. As shown in this figure, the blade is mounted on the tip end of a member 23 which is mounted on a base stand 22 so that the tip of the blade is in contact with the recording surface of a magnetic tape 1 at a predetermined angle. The base stand 22, the member 23, and the blade 24 constitute the tape cleaner.
In the case of reel driving, the magnetic tape 1 drawn out from the supply reel 2 is transported in the direction indicated by the arrow x in FIG. 7, and then it is guided by the tape guides 4 and 5, guide pin 6, and tape guides 7, 9 and 10, so that it is guided to be wound around the rotary magnetic head apparatus 11 which is rotating in the direction indicated by the arrow y. Further, the magnetic tape is guided by the tape guides 12, 13, 14, 17, 18, 19 and 21 in order, and then taken up by the takeup reel 3.
During this transportation, when a video signal or an audio signal is recorded, oblique tracks are formed on the recording surface of the magnetic tape 1 by a rotary magnetic head (not shown) on the rotary magnetic head apparatus 11. Further, a control signal is recorded by the CTL head 15 and various signals are recorded by the recording and reproducing head 16. Furthermore, the control signal recorded by the CTL head 15 is reproduced by the CTL head 20 to confirm proper recording. In addition, dust, magnetic powder or the like attached on the magnetic tape 1 are removed from the magnetic tape 1 by the tip portion of the blade 24, whereby reduction in dropout and prevention of deterioration in error rate are intended.
FIG. 8 is an enlarged view of the tape cleaner in FIG. 7 showing the transportation path of the magnetic tape 1 between tape guides 7 and 9. As shown in FIG. 8, the left tip portion 24a of the blade 24 is urged against the magnetic surface of the magnetic tape 1 at an angle .theta.3. By making such an angle, magnetic powder dropped from the magnetic tape and dust are removed upon reproduction. The angle .theta.3 of the tip portion 24a of the blade 24 relative to the magnetic tape 1 is substantially equivalent to the wrapping angle .theta.b of the magnetic tape 1 relative to the blade 24. This is because upon microscopic observation the tip portion 24a of the blade 24 is round.
The wrapping angle (not shown) of the tape 1 around the full erase head 8 is set to 10.791.degree., the width w1 is set to 0.99 mm, the angle .theta.2 of the left side tip portion 24a c,f the blade 24 with respect to the bottom portion of the blade 24 is set to 60.degree., the angle .theta.3 between the line drawn from the bottom face 24b of the blade 24 and the line drawn from the path of the magnetic tape 1 as it approaches the tip portion 24a is set to 15.3357.degree.. Further, the angle .theta.c between the magnetic tape 1 and the bottom portion of the blade 24 is set to 6.degree., and the angle between the magnetic tape 1 after passing tip portion 24a and the line drawn from the path of the magnetic tape 1 as it approaches the tip portion 24a is set to 9.3357.degree..
Further, in addition to the above-described tape cleaner, there has been proposed an apparatus in Japanese Patent Laid-Open Gazette No. 3-10387, in which a polygonal-shaped body has a blade disposed at each corner thereof and is intermittently rotated so that dust and magnetic powder attached to the magnetic tape are removed. The dust and magnetic powder attached to the blades are then cleaned by a brush-like secondary cleaner.
Further, the present applicant has previously proposed a tape cleaner in which the blade is brought into contact with the recording surface of the tape during tape transportation at a low speed, thereby removing dust and magnetic powder while the blade is separated from the recording surface of the tape during tape transportation at a high speed (see Japanese Patent Laid-Open Gazette No. 3-203079).
If a microscopic observation is made on the tip portion 24a of the blade 24 of the above-described tape cleaner, it is found that the magnetic surface of the magnetic tape 1 is not intimately in contact with the tip portion 24a. If intimate contact is not made, there can be a chance that dust and magnetic powder attached to the magnetic tape 1 cannot be removed completely. Further, if the dust and magnetic powder strongly adhere to the magnetic tape 1, it is difficult to remove them.
The dust and magnetic powder which are left unremoved by the blade 24 enter the rotary magnetic head apparatus 11, causing dropout upon reproduction. In addition, if the magnetic recording and reproducing apparatus in which the tape cleaner is provided is requested to satisfy a highly demanding error rate, as described above, it is unsatisfactory to provide only the single blade 24 to remove the dust and magnetic powder on the magnetic surface side of the magnetic tape 1.
Further, if the dust and magnetic powder that have been removed are collected on the blade 24, then the collected dust and magnetic powder again adhere to the magnetic tape 1 when the magnetic tape 1 is transported in the reverse direction, as indicated by the arrow z in FIG. 7. Moreover the collected dust and powder can cause head clog on the magnetic head (not shown) that is mounted on the rotary magnetic head apparatus 11 or also can cause dropout upon reproduction when the recording or reproduction is again performed.